According to the forecast by India Meteorological Department (IMD), all districts of south Bengal, including Kolkata, are expected to get widespread rainfall on Friday and Saturday.

From Monday, July 29 to August 1, districts across Bengal are expected to get widespread rain, with above-average rain in almost the entire southern region.

The reason behind the widespread rain is the monsoon trough that is now the closest to Kolkata that it has been this monsoon. The monsoon trough is an imaginary line connecting various low-pressure points from the western part of the country to the eastern part.

“A cyclonic circulation lies over Gangetic West Bengal and adjoining Bangladesh and extends up to 7.6 km above mean sea level tilting southwards with height. There is a possibility that the system descends and takes the form of a low-pressure area,” said Somenath Dutta, head of IMD, Kolkata.